Optimal operation of a coal-nuclear-pumped storage hybrid system considering supporting capacity evaluation

Abstract With the increasing penetration of renewable energy and the gradual retirement or transformation of coal-fired power plants, the conflict between decarbonization and power-supply reliability in power systems has become increasingly prominent. To solve the problem, this paper proposes an optimal operation method for a coal-nuclear-pumped storage hybrid system that incorporates an evaluation of powersupporting capacity. The feasibility of partially replacing the functions of coal-fired power plants is analyzed. Firstly, a supporting capacity evaluation framework is developed for supportive power sources, encompassing power and energy support as well as flexibility-regulation capability support. Secondly, the short-term power and flexibility-regulation capability support requirements are assessed. By introducing the concept of ordered clustering, a net load segmentation method based on Fisher optimal segmentation is proposed to analyze the impact of seasonal fluctuations in both renewable energy and load on long-term energy support in power systems. Thirdly, a nuclear-pumped storage joint operation model is constructed for three operation modes: full tracking mode, three-stage tracking mode, and partial tracking mode. Finally, an optimal operation model is established for the hybrid system, aiming to minimize the comprehensive operational cost of the power system while considering supporting capacity evaluation. Case study results validate the effectiveness and rationality of the proposed model and method, and demonstrate the significant potential of nuclear-pumped storage joint operation in replacing the functions of coal-fired power plants.